The last time Senate Democrats brought up an international disabilities treaty Republicans were deeply divided.

In the final weeks of the 112th Congress, former Senate Majority Leader Robert Dole, then 89, frail and in a wheelchair pushed onto the Senate floor by his wife, former Sen. Elizabeth Dole, R-N.C., could not rally enough GOP support to approve the United Nations disability treaty. Republicans put their heads down and voted against the pleadings of the World War II veteran who, the week before, had been receiving treatment at Walter Reed National Medical Military Center. The treaty fell five votes short of the two-thirds majority necessary to pass it.

The Foreign Relations panel is scheduled to hold a two-part hearing on the treaty Tuesday at 2:30 p.m., with the first panel anchored by Sen. Kelly Ayotte, R-N.H. — one of eight Republicans who voted with Democrats the first time around — and Sen. Mark S. Kirk, R-Ill., a Naval reserve veteran who suffered a stroke in January 2012 and faces physical impediments as a result. In the second panel, Rep. Tammy Duckworth, D-Ill., a veteran who lost her legs in Iraq, and former Homeland Security Secretary Thomas Ridge, who now chairs the National Organization on Disability, are among the notable speakers.

Another former Senate Republican leader, Bill Frist, penned an op-ed Tuesday defending the treaty and challenging its detractors.

"As is often the case, a bit of politics and a bit of misinformation ruled the day," Frist wrote in Reuters of the failed December 2012 vote. "Two larger political issues emerged. Republicans exhibited some squeamishness around the term 'sexual and reproductive health' in the treaty. While the term is undefined, there were rumblings that it could create a global right to abortion.

"The second issue was an impressive fear campaign launched by Michael Farris of the Home School Legal Defense Association to convince parents that the U.N. treaty would limit their ability to educate their disabled children at home," Frist continued.

He goes on to say that the reproductive health language does not define services but rather ensures that disabled people are granted the same protections as others and that nothing in the treaty would override the Americans With Disabilities Act, on which the U.N. treaty is modeled.

With 55 Democrats and five Republicans who voted in favor for the treaty last time, supporters need to find a handful of GOP senators to break ranks and approve the treaty. Kirk would bring the whip count to 61 and Sen. Thad Cochran, R-Miss. — who switched his vote from "yes" to "no" during the 2012 vote when it appeared backers would not clear their threshold — also could be a "yes" this time.

Look for Republicans Bob Corker and Lamar Alexander of Tennessee to be top targets for vote-switching, as Corker now is the ranking member on Foreign Relations. Other Republicans to watch might be Lindsey Graham of South Carolina (Ayotte and John McCain of Arizona both voted for the treaty in 2012), Dean Heller of Nevada, Rob Portman of Ohio and Jerry Moran of Kansas (whose late decision to cast a "no" vote in 2012 was viewed largely as the final move that collapsed its chances of passage).